The present invention relates to electrical fuse blocks for mounting in cabinets and having rotary disconnect shafts extending out of the cabinets to a handle, and in particular, to a fuse block in which the handle may be mounted on the side of the cabinet yet which provides an interlock limiting operation of the fuse block when a cabinet door is open.
Fuse blocks, as are well known in the prior art, provide one or more sockets for receiving standard electrical fuses having a fusible link that will melt and separate when excessive current is drawn through the fuse. The fuse block may include terminals for attaching power connections to the fuse block, and thus serves to simplify the wiring of the fuses into series with power carrying conductors.
It is common to mount one or more fuse blocks in a cabinet having a door that may be closed to prevent inadvertent access to exposed conductors inside. The fuse block may incorporate a disconnect allowing disconnection of power from the fuse block. The disconnect may be used when fuses need to be changed or when it is necessary to remove power from the fuse connected circuits and the associated equipment when the equipment is idle or must be worked on.
The disconnect may be operated by a rotary shaft extending forward from the fuse block through the door cabinet to be received by a handle held on the cabinet door. The handle allows power to be disconnected without opening the cabinet door and exposing the internal wiring. The handle may, in addition, have a lockout accepting a padlock and preventing turning of the handle to reconnect power except by the holder of the padlock key. In addition, the handle may be designed to grip the shaft except when the disconnect is in the open circuit position, thus preventing opening of the cabinet door until power is removed from the fuse block. In this way, an interlock is provided to prevent unintended opening of the cabinet when the fuse block is connected.
In an alternative configuration of the fuse block, the shaft may extend out of a side of the cabinet to be received by a handle mounted on the sidewall of the cabinet. In this case, the handle is always connected with the fuse block shaft and thus does not serve as an interlock to hold the door closed when the fuse block is connected to power.
Generally, the fuse blocks will be placed in a wide variety of cabinets of different sizes and in different locations within the cabinets. What is needed is an interlock system for such a fuse block using a side mounted handle that works with a variety of different cabinet sizes and placements.
The present invention provides a door interlock system that works with a fuse block having side mounted handles. A finger is attached to the door to provide an indication that the door is shut and a means for locking the door when the fuse block is powered. The interlock accommodates over travel of the finger thus allowing a single finger or small number of standard fingers to accommodate a variety of different cabinet dimensions and mounting conditions.
Specifically, the present invention provides a disconnect mechanism for a fuse block, where the fuse block receives power connections and has a support face for mounting against the rear panel of a cabinet to hold one or more fuses accessible from a front face of the fuse block opposite the support face. The disconnect mechanism provides a rotary shaft communicating with the fuse block and extending outward along the rear panel when the support face of the fuse block is mounted against the rear panel. An outer end of the rotary shaft is adapted to receive a portion of a door handle mounted on the side of the cabinet so that the rotary shaft can be rotated by the handle to disconnect the fuses from the power connections.
A bolt operator extends radially from the rotary shaft to rotate therewith and provide a stop surface that may be engaged by a bolt, the bolt moving between a lock position and an unlock position. In the lock position, the bolt engages the stop surface preventing free rotation of the rotary shaft to connect the fuses to power. In the unlock position, the bolt is disengaged from the stop surface allowing free rotation of the rotary shaft to connect the fuses to power. A finger mounted on the lid of the cabinet engages the bolt when the lid is closed to move the bolt to the unlocked position.
It is thus one object of the invention to prevent inadvertent connection of the fuse block to power when the cabinet door is open. When the cabinet door is open, the finger on the lid is withdrawn leaving the bolt in the locked position preventing free rotation of the rotary shaft to the xe2x80x9cONxe2x80x9d position.
The bolt operator may further provide a bolt-retracting surface engaging the bolt to move the bolt to a door release position. The bolt may engage the finger to prevent opening of the cabinet door when the bolt is not in the door release position. The bolt-retracting surface may engage the bolt only when the rotary shaft is positioned to disconnect the fuses from the power connections.
Thus, it is another object of the invention to prevent opening of the door inadvertently when power is connected to the fuse block.
The finger may include a cam surface moving the bolt to the unlocked position when the door is fully closed.
Thus it is another object of the invention to allow for free reconnection of the fuse block when the door is closed.
The bolt may be a lever centrally mounted on an axle extending parallel to the rotary shaft. The lever may pivot about the axis of the axle to move between the locked and unlocked positions.
Thus it is another object of the invention to provide a simple mechanism to produce the interlock of the present invention.
The axle may be sized to extend through a sidewall of the cabinet when the support face of the fuse block is mounted in the cabinet.
Thus it is another object of the invention to allow overriding of the door-locking interlock in the event that it is necessary to have access to the cabinet while the power is on. It is an additional object of the invention to provide for this ability to defeat the locking of the door from a position near the handle that is accessible to the user. The end of the axle may extend outside of the cabinet and there, shrouded by a tube, may have a screw head to allow actuation of the bolt with a standard screwdriver fitting within the shrouded tube.
Thus it is another object of the invention to prevent inadvertent defeating of the door lock.
The lever may include a spring rotationally biasing the lever toward engagement with the bolt operator.
Thus it is another object of the invention to provide an interlock that may be overcome when the cabinet door is open in a secondary operation by moving the lever against its biasing spring manually.
The handle attachable to the sidewall of the cabinet to engage the rotary shaft may have a means for receiving a padlock to prevent rotation of the handle.
Thus it is another object of the invention to provide for an absolute lockout of the fuse block that may not be defeated even when the cabinet door is open. Because the handle is always connected to the rotary shaft, locking of the handle is sufficient in this regard.
It is another object of the invention to provide such a lockout that does not prevent access to the interior of the cabinet. Unlike a locking of a front handle, a locking of a side-mounted handle does not prevent opening of the door.
The bolt operator may be a cam disk and the stop and bolt-retracting surfaces may be portions of the periphery of the cam disk. Thus it is another object of the invention to provide an extremely simple mechanism for realizing the interlocks that are required.
The fuse block may include a fuse block shaft extending outward along a side face of the fuse block to be substantially perpendicular to the rear panel when the support face is mounted against the rear panel, and the fuse block shaft may support a gear having radially outward teeth, and the bolt operator plate may include a series of corresponding slots whose separations form teeth engaging teeth on the gear of the fuse block shaft whereby torque on the rotary actuator may be converted to corresponding torque on the fuse block shaft.
Thus it is another object of the invention to provide a kit for converting a standard fuse block having a forwardly extending rotary shaft for use with a side mount handle configuration using a thereby simplifying stocking and manufacturing of fuse blocks.
The above objects and advantages may apply to only some embodiments falling within the claims and thus do not define the scope of the invention.